Effect of vegetation on the impact of a severe blowdown in the southern Rocky Mountains, USA

In October 1997, a storm with winds estimated at 200-250 km/h blew down a large percentage of trees in over 10,000 ha of subalpine forest in northern Colorado, USA. In a case study, we analyzed the effect of pre-blowdown tree density, cover-type, and stand structural stage on the percentage of trees blown down. Low tree density led to somewhat lower levels of blowdown than did higher density. Effects of cover-type and habitat structural stage on the pattern of damage from the blowdown varied spatially. At lower elevations, farther from the source of the winds coming over the Continental Divide, aspen forests were less susceptible to blowdown than expected, whereas spruce-fir forests were more susceptible than expected. At higher elevations, closer to the source of the winds, habitat structural stages representing earlier stages of stand development were much less susceptible to blowdown than expected, whereas more advanced structural stages were generally more susceptible to blowdown than expected. Overall, the effects of density, composition, and structural stage on the pattern of damage were modest, but evident. That there is a detectable effect of vegetation composition and structure across this large blowdown implies that, even during extreme wind events, vegetation can influence the extent and pattern of damage, more strongly so in some places than in others. © 2002 Elsevier Science B.V. All rights reserved

Features of Quark and Lepton Mixing from Differential Geometry of Curves on Surfaces

It is noted that the CKM matrix elements for both quarks and leptons as conceived in the Dualized Standard Model (DSM) can be interpreted as direction cosines obtained by moving the Darboux trihedron (a 3-frame) along a trajectory on a sphere traced out through changing energy scales by a 3-vector factorized from the mass matrix. From the `Darboux' analogues of the well-known Serret--Frenet formulae for space curves, it is seen that the corner elements ($V_{ub}, V_{td}$ for quarks, and $U_{e3}, U_{\tau 1}$ for leptons) are associated with the (geodesic) torsion, while the other off-diagonal elements ($V_{us}, V_{cd}$ and $V_{cb}, V_{ts}$ for quarks, and $U_{e2}, U_{\mu 1}$ and $U_{\mu 3}, U_{\tau 2}$ for leptons) with the (respectively geodesic and normal) curvatures of the trajectory. From this it follows that (i) the corner elements in both matrices are much smaller than the other elements, (ii) the $U_{\mu 3}, U_{\tau 2}$ elements for the lepton CKM matrix are much larger than their counterparts in the quark matrix. Both these conclusions are strongly borne out by experiment, for quarks in hadron decays and for leptons in neutrino oscillations, and by previous explicit calculations within the DSM scheme.Comment: 10 pages, Latex, 3 figures using ep